p87c770aar NXP Semiconductors, p87c770aar Datasheet - Page 75

• Manufacturer Part Number: p87c770aar
• Description: Microcontrollers Ntsc With On-screen Display Closed Caption
• Manufacturer: NXP Semiconductors

Philips Semiconductors
25 RELEASE LETTER OF ERRATA
25.1
A correction is possible after the next frame, which results
in the stopped soft scroll (0.2 after soft scroll has been
started a stop soft scroll is sent) to sometimes generate a
display flicker.
The automatically incremented DPTR didn’t work
correctly.
A move command to the display memory
(MOVX @DPTR,A) or (MOVX A, @DPTR) sometimes
delivers a wrong result (e.g. an ‘A’ should be written/read
but a ‘B’ is stored/read in/from the memory).
A software workaround has been designed.
1999 Jun 11
The soft scroll active bit and the top scroll row are not
synchronized. Therefore, it is not possible to calculate
from this bit and the top scroll row the current base row
(the row which is displayed as the lowest one or which
scrolls in). The top scroll row number is incremented
immediately after the soft scroll function is finished but
the soft scroll active bit remains set. The soft scroll
active bit is cleared one field/frame later. A software
workaround is implemented.
If the soft scroll function is to be stopped (write 0
OSD Status Register) the soft scroll should stop
immediately, but it stops at the end of the field/frame.
After stopping the soft scroll function the soft scroll
active bit should be cleared and the top scroll row
number (lower 4 bit of the OSD Status Register) should
be incremented by one. But sometimes the top scroll
row number is incremented by two. Also in the stopped
soft scroll the display sometimes jumps out of the
defined scroll range. For example, the range is defined
from row 0 to 5 and row 8 to 14 is displayed.
Read/Write problem with access to Display Memory by
the CPU. The error rate is 1/84000 (synchronized
clock). The error is synchronous to the HSYNC with
approximately 11 s delay after HSYNC.
Microcontrollers for NTSC TVs with On-Screen
Display (OSD) and Closed Caption (CC)
Bugs with a software workaround
20 to
75
25.2
25.3
According to the CC specification the time between stop
and start should be no more than 0.433 seconds.
With the method as implemented the start command will
be issued after 0.46 seconds.
The specification has been changed to ‘the soft scroll
function with double height rows is forbidden’.
The foreground colour of the first character behind a
double size/width attribute is ignored.
During a double height row, if shadow is active, a north
shadow appears above the last line of the row whether
the underline is active or not.
Soft scroll function cannot be stopped immediately
(behaviour is not specified in the specification). If the
decoder wants to terminate the soft scroll function, the
soft scroll function stops one field/frame later. A restart
is not possible before the scrolling has stopped.
Therefore, a restart of the soft scroll function must be
delayed by one field/frame. A software workaround is
implemented.
The OSD does not allow the active edges of HSYNC
and VSYNC to come at exactly the same moment
Soft scroll does not work, if a double height row is the top
row of the scroll area.
Bugs with no workaround
Specification problems (unspecified)
P8xCx70 family
Product specification